Typical Orienting but Impaired Processing of Social Information in Infants At-Risk for ASD

Background:  Developmental theories of autism spectrum disorders (ASD) can be broadly divided into those that see the social and communication difficulties as emerging from impairments in processing social information (Baron-Cohen, Leslie & Frith, 1985; Gliga et al, 2012) and those that propose they stem from an inability to orient to or attend to the social world (Dawson et al., 2004; Chevalier at al, 2012). According to the second account diminished early “social” orienting biases, for example, would limit the exposure to social interaction and have cascading effects on learning from and about people. These orienting mechanisms are subserved by evolutionarily conserved (Shepherd, 2010) sub-cortical and cortical structures (Johnson, 2005) that are functional from very early in life in typical development. Prospective studies of infants at-risk for ASD offer the ideal opportunity for testing they are impaired very earlier in development in ASD.

Objectives:  We present emerging findings from the British Autism Study of Infant Siblings (BASIS; http://www.basisnetwork.org/) investigating the ability to orient to and engage with a variety of “social” stimuli, during the first year of life.

Methods:  We have used an eye-tracker (Tobii) to measure infant’s ability to (1) orient to faces presented amongst other distractors, in a static visual search display (Elsabbagh et al, 2012); (2) orient to eye, mouth or hand movements and (3) to follow someone’s head and eye gaze to a proximal object (Bedford et al, 2012). Fifty-four infants at high risk for ASD (because of having an older sibling with the disorder) and 50 infants with no family history of ASD, therefore at low risk, took part in a longitudinal study. Infants were seen at 7 and 13 months of age and then again after their 3^rdbirthday. Following a clinical assessment at the latter age high-risk siblings were classified as having developed ASD (HR-ASD), other atypicalities (HR-Aty) or no atypicalities (HR-TD).

Results:  We found no evidence for difficulties with orienting to faces, eyes or human actions in infants that later developed an ASD. At all ages HR-ASD oriented to faces and remained engaged with them to the same extent as the other HR or LR participants. HR-ASD showed no difficulties orienting to the eyes of a face in a static display or to eye, mouth or hand movements. No difference was found between groups in terms of correctly following someone’s gaze. However subtle differences appeared when analyzing the amount of time infants spent looking at someone’s object of interest, in the gaze following study. 

Conclusions:  Across three eye-tracking studies we found little evidence for an impairment in “social orienting” biases during the first year of life in those infants that go on to develop an ASD. These results agree with previous findings of gradual decrease in social engagement later during childhood (Swettenham et al, 2003; Chawarska et al, 2009) possibly as a result of earlier difficulties with processing social information, e.g. difficulties understanding the communicative function of social cues like gaze and head shifts.